In this case the "$(cat /path/to/sample.txt)" portion of the command will read out the contents of that file to the command line as a string. I put single quotes ' around that command to break the surrounding portions of the text into two separate strings. I put double quotes " around those in order to ensure that the text file being read in is enclosed as a string to the json object being passed to NLU. Sorry for the confusion before - that was an error on my part and it should work now.

What the command line sees is 3 different strings that it joins together: